e-Boekhouden MCP Server and API by Cotlet

Open the browser

cotlet_browser_open

Read-only

Starts the user's Cloud Browser (a real Chrome on Cotlet, where the user is signed in to their sites) and opens url. Call it first. The URL goes to the site's open tab, else to a new tab, so the user's own tabs stay. Answers the page after it: the elements and text in view, with the same numbers. In e-Boekhouden it serves these actions: Create invoice, Book mutation, Add relation, List open items, Export ledger.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "cotlet_browser_open"
  }
}

Input Schema

Name	Required	Description	Default
`app`	No	Leave it out: the step runs in the user's web browser. Only when cotlet_app_guide names an app's own Cloud Browser, that app's slug, e.g. milanote.
`url`	No	A public http or https address, e.g. https://example.com.

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 9, 2026

TDQS

A4.1/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Goes well beyond the annotations by disclosing that this is a real Chrome session with the user's existing logins, that the URL reuses the site's open tab before creating a new one so the user's own tabs are preserved, and that the page state (elements and text in view, with the same numbering) is returned after the call. That is exactly the behavioral context an agent needs for a stateful, open-world browser action.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loads the core action and ordering rule, then adds return behavior. Sentences are dense but each carries information; the trailing e-Boekhouden action list is slightly bolted-on yet useful for routing to downstream tools.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a two-parameter, no-output-schema tool, the description covers invocation order, tab semantics, the signed-in session, and what is returned. The one gap is that its relationship to cotlet_browser_navigate and cotlet_browser_wait is left implicit.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and both parameters are already documented in the schema, including the 'leave it out' instruction for app. The description reinforces that the URL lands in the user's browser but adds no format or syntax detail beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a concrete verb and resource: starts the user's Cloud Browser (a real Chrome session where the user is signed in) and opens the given url. The 'Call it first' instruction signals it is the entry point of the browser tool family, though it never explicitly contrasts itself with the sibling cotlet_browser_navigate.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear ordering guidance ('Call it first') and explains the tab-targeting rule so the agent knows what will happen. It also scopes app usage via 'Leave it out: the step runs in the user's web browser', but does not say when to prefer cotlet_browser_navigate or cotlet_browser_tabs instead.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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